We propose to continue our research aimed at resolving the contribution of each of the four afferent visual systems to the mediation of innate visual behavior (attention, orientation, tracking, stereopsis), learned discrimination (flux, pattern), and interhemispheric transfer of leaned behavior in the cat. A primary aim is to find out whether learning of pattern discrimination is mediated by the same areas of the brain which are required for interhemispheric tranfer of such learning. Our work is directed toward both subcortical and cortical centers of these visual systems and to the interaction between them. Of special interest are the seveal cortical areas of the extra-geniculate systems and the superior colliculus. We are attempting to uncover the neural mechamism responsible for the blindness (amblyopia) which follows certain cortical lesions in the superior colliculus and its commissure. The physiological activity mediated by the tectal and posterior commissures, and their role of interhemispheric transfer is also being studied. In pursuing these ends, we will use anatomical, electrophysiologial and behavioral methods.